Why would you want to use Whatsapp web on a phone?
– Firelord♦Feb 14 at 22:56

The biggest issue is if you are looking to use WhatsApp Web on your primary device associated with your WhatsApp account, you will be unable to scan the QR code at any rate to validate.
– justamarkprimeMar 20 at 12:23

1

@Firelord I assume OP wanted to mirror WhatsApp account on another Android device (which might make this an XY problem if that's the case) since according to WhatsApp FAQ, you can only use 1 account on 1 device, if I didn't misinterpret it.
– Andrew T.♦Mar 20 at 14:32